Question: If $h(x)$ is a function whose domain is $[-8,8]$, and $g(x)=h\left(\frac x2\right)$, then the domain of $g(x)$ is an interval of what width?
Answer: Since we defined $g(x) = h\left(\frac{x}{2}\right)$, a real number $x$ is in the domain of $g$ if and only if $\frac{x}{2}$ is in the domain of $h$.  Therefore, the domain of $g$ consists of all $x$ such that $$-8\le \frac x2\le 8.$$The solutions to this inequality are given by $-16\le x\le 16$, so the domain of $g$ is an interval of width $16 - (-16) = \boxed{32}$.